<?php
/**
* Global Search Engine for Moodle
*
* @package search
* @category core
* @subpackage document_wrappers
* @author Valery Fremaux [valery.fremaux@club-internet.fr] > 1.8
* @date 2008/03/31
* @license http://www.gnu.org/copyleft/gpl.html GNU Public License
*
* this is a format handler for getting text out of a proprietary binary format 
* so it can be indexed by Lucene search engine
*/

/*
* first implementation is a trivial heuristic based on ppt character stream :
* text sequence always starts with a 00 9F 0F 04 sequence followed by a 15 bytes
* sequence
* In this sequence is a A8 0F or A0 0F or AA 0F followed by a little-indian encoding of text buffer size
* A8 0F denotes for ASCII text (local system monobyte encoding)
* A0 0F denotes for UTF-16 encoding
* AA 0F are non textual sequences
* texts are either in ASCII or UTF-16
* text ends on a new sequence start, or on a 00 00 NULL UTF-16 end of stream
*
* based on these following rules, here is a little empiric texte extractor for PPT
*/

/**
* @param object $resource
* @uses $CFG
*/
function get_text_for_indexing_ppt(&$resource, $directfile = ''){
	global $CFG;

	$indextext = null;
	
	// SECURITY : do not allow non admin execute anything on system !!
	if (!has_capability('moodle/site:doanything', get_context_instance(CONTEXT_SYSTEM))) return;

	if ($directfile == ''){
		$text = implode('', file("{$CFG->dataroot}/{$resource->course}/{$resource->reference}"));
	} else {
		$text = implode('', file("{$CFG->dataroot}/{$directfile}"));
	}
	
	$remains = $text;
	$fragments = array();
	while (preg_match('/\x00\x9F\x0F\x04.{9}(......)(.*)/s', $remains, $matches)){
		$unpacked = unpack("ncode/Llength", $matches[1]);
		$sequencecode = $unpacked['code'];
		$length = $unpacked['length'];
		// print "length : ".$length." ; segment type : ".sprintf("%x", $sequencecode)."<br/>";
		$followup = $matches[2];
		// local system encoding sequence
		if ($sequencecode == 0xA80F){
			$aFragment = substr($followup, 0, $length);
			$remains = substr($followup, $length);
			$fragments[] = $aFragment; 
		}
		// denotes unicode encoded sequence
		elseif ($sequencecode == 0xA00F){
			$aFragment = substr($followup, 0, $length);
			// $aFragment = mb_convert_encoding($aFragment, 'UTF-16', 'UTF-8');
			$aFragment = preg_replace('/\xA0\x00\x19\x20/s', "'", $aFragment); // some quotes
			$aFragment = preg_replace('/\x00/s', "", $aFragment);
			$remains = substr($followup, $length);
			$fragments[] = $aFragment; 
		}
		else{
			$remains = $followup;
		}
	}
	$indextext = implode(' ', $fragments);
	$indextext = preg_replace('/\x19\x20/', "'", $indextext); // some quotes
	$indextext = preg_replace('/\x09/', '', $indextext); // some extra chars
	$indextext = preg_replace('/\x0D/', "\n", $indextext); // some quotes
	$indextext = preg_replace('/\x0A/', "\n", $indextext); // some quotes
	$indextextprint = implode('<hr/>', $fragments);

	// debug code
	// $logppt = fopen("C:/php5/logs/pptlog", "w");
	// fwrite($logppt, $indextext);
	// fclose($logppt);
	
	if (!empty($CFG->block_search_limit_index_body)){
		$indextext = shorten($text, $CFG->block_search_limit_index_body);
	}

	$indextext = mb_convert_encoding($indextext, 'UTF8', 'auto');
	return $indextext;
}
?>